Question

2. Use the Henderson-Hasselbalch equation to estimate the pH of a buffer solution that is composed of 20 mL of 10 M sodium formate and 20 mL of 1 M formic acid. (Note: the pKa of formic acid is 3.75).

Answer 1

Answer:

pH of buffer =4.75

Explanation:

The pH of buffer solution is calculated using Henderson Hassalbalch's equation:

$pH=pKa+log[\frac{[salt]}{[acid]}$

Given:

pKa = 3.75

concentration of acid = concentration of formic acid = 1 M

concentration of salt =  concentration of sodium formate = 10 M

$pH=3.75+log[\frac{10}{1}]=3.75+1=4.75$

pH of buffer =4.75